ZCZC SPCSWODY1 ALL ACUS01 KWNS 121629 SPC AC 121626 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 121630Z - 131200Z NO SVR TSTM AREAS FCST. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 N HVR WEY 40 SSW BYI 40 NE BIH 20 NW SMX. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 55 SSW SJT 20 N BWD 45 NE ACT 35 NNE CLL 60 SE AUS 35 S SAT 45 ESE DRT 55 SSW SJT. ...SYNOPSIS... UPPER LOW OFF THE WA/ORE COAST EXPECTED TO DRIFT SE TOWARD THE NRN CA COAST THIS PERIOD AS DOWNSTREAM TROUGH EDGES E ACROSS THE CNTRL PLAINS. ONE EMBEDDED SHORTWAVE TROUGH NOW OVER NE ORE SHOULD CONTINUE NNE ACROSS NRN ID/NW MT LATER TODAY. SIMILAR IMPULSE NOW APPROACHING THE NW CORNER OF CA SHOULD AFFECT SW ORE/NRN CA LATER TODAY/TONIGHT. ELSEWHERE...WRN EXTENSION OF DISTURBANCE CENTERED OVER SE TX AND THE NWRN GULF SHOULD CONTINUE TO EDGE SEWD AWAY FROM CNTRL/ERN TX. ...NWRN U.S... THUNDERSTORMS MAY INCREASE IN COVERAGE OVER HIGHER TERRAIN OF CNTRL ID/WRN MT LATER TODAY...WHERE STRONGEST HEATING WILL OCCUR DOWNSTREAM FROM NE ORE UPPER IMPULSE. ANOTHER AREA OF MORE CONCENTRATED ACTIVITY EXPECTED LATER TODAY AND TONIGHT OVER SRN ORE/NW CA...AS COOL UNSTABLE ONSHORE FLOW DEVELOPS IN WAKE OF UPPER DISTURBANCE NOW OFF THE NW COAST OF CA. FARTHER S...A FEW EMBEDDED THUNDERSTORMS MAY ACCOMPANY FRONTAL BAND ASSOCIATED WITH IMPULSE OFF THE NW CA COAST AS THE FRONT SETTLES SLOWLY S ACROSS NRN AND CNTRL PARTS OF THE STATE LATER TODAY/ TONIGHT. CONSIDERABLE DEEP SHEAR WILL DEVELOP ACROSS THE REGION LATER TODAY AS MID LEVEL SSWLY FLOW INCREASES TO AOA 50 KTS. MODERATE TO STRONG LOW LEVEL SHEAR WILL ALSO BE PRESENT... ESPECIALLY OVER NRN PARTS OF THE CENTRAL VALLEY WHERE CHANNELING WILL MAINTAIN A SLIGHT ELY COMPONENT TO THE NEAR-SURFACE FLOW. WHILE ANY SUSTAINED UPDRAFTS IN THIS ENVIRONMENT MAY DEVELOP SOME LOW TO MID LEVEL ROTATION...THREAT FOR SEVERE WILL BE LIMITED BY MARGINAL DEGREE OF SURFACE-BASED CAPE. ...TX... DIURNAL HEATING MAY INITIATE ISOLATED SURFACE-BASED STORMS OVER CNTRL TX THIS AFTERNOON...ON WRN FRINGE OF WITHDRAWING UPPER DISTURBANCE. GRADUAL WARMING ALOFT AND ABSENCE OF A WELL-DEFINED SURFACE FOCUSING MECHANISM SHOULD...HOWEVER...LIMIT COVERAGE/ INTENSITY OF ANY SUCH DEVELOPMENT. ..CORFIDI/TAYLOR.. 04/12/03 NNNN |